Generally, this invention relates to a system for and methods of easily and securely inserting and removing a fastener that in at least one application is used during orthopedic surgery to promote proper healing of injured bone. Specifically, the invention focuses upon a fastener and a corresponding driver that is usable to insert and remove the fastener in a manner that reduces the chance of slippage of the driver from the fastenerxe2x80x94a problem in orthopedics, other branches of health care, and fastening generally.
Fasteners with threads, or screw fasteners, are commonly used to hold broken bones in place during healing and to attach orthopedic healing aids such as plates or rods to broken bones. In many healing applications, the fastener should have the ability to draw pieces of the bone into intimate contact, and/or the orthopedic healing aid into intimate contact with the bone(s) or bone pieces. The torque required to achieve this may be delivered by an insertion device or driver. Ideally, the fastening system will allow for quick insertion to minimize the time required for the procedure and will have sufficient engagement with the insertion device to prevent positional divergence such as slippage of the driver from the fastener which could cause the fastener to be improperly positioned and/or cause additional damage to the bone, among other problems. Additionally, the system will allow for secure non-slip insertion of the fastener without requiring an improperly high compressive force be imparted by a user to the driver. Finally, a removal device (which may be the same as the insertion device) must be able to securely reengage the fastener so it can be removed from the bone with a minimized chance of positional divergence of the driver from the fastener, also without requiring the application of an improperly high compressive force into the fastener to assure secure removal of the fastener.
Efforts in the driver/fastener system field have tended to focus on the design of thread systems to ensure intimate contact of bone fragments and/or of the orthopedic healing aid with bone(s). Examples of these efforts may be illustrated in U.S. Pat. Nos. 6,022,352, 6,083,227, and 5,871,486. While these technologies address an important problem, considerably less effort has been applied to the equally important problem of quickly, safely, and securely inserting and removing bone screw fasteners. Examples of efforts in this specific area are illustrated in U.S. Pat. Nos. 5,885,286; 6,048,343; 6,183,472; and 5,997,538. Several of these approaches are complex mechanical assemblies consisting of many small parts which may be difficult to assemble and manipulate, and that pose a hazard to the patient during orthopedic surgery. Often, the physician must take additional time to use these devices and ensure their proper assembly and disassembly. Thus, there is a need for a fastener/driver device that is not a complex mechanical assembly and that exhibits a positive, non-slip engagement between driver and fastener. Although this problem is well known on orthopedics and other fields of endeavor, the need for a simple system that facilitates the rapid, reliable and secure insertion and removal of fasteners has not been adequately met.
The present invention includes a variety of aspects and features which may be applied in various ways depending on the exact application or need to be addressed. At least one embodiment of his invention involves a system for the rapid and reliable insertion and removal of fasteners for use in orthopedic surgery and other applications requiring such capability. This system may include a fastener and a tool such as a driver that is usable for insertion and removal of the fastener. In one basic form, the invention provides a system for positive, complete tri-modal retention of a fastener by a fastener driver so that during operation of the system in a fully engaged configuration and under design loads, three types of positional divergence of the driver relative the fastenerxe2x80x94bi-axial, bi-rotational, and bi-lateralxe2x80x94are prevented. Thus, relative to conventional fastener/driver systems, the fastener can be inserted and removed by the driver more quickly and with a reduced possibility of slippage, stripping, or other hazardous, undesired positional divergence of the driver from the fastener. The system is designed to better meet the needs of both the patient and the physician in orthopedic surgery and other areas of health care. It may also find use in other fastening applications such as structural assembly, whether in fields such as aerospace, aircraft or carpentry, as but a few examples.
An object of at least one embodiment of the invention is to provide an insertion/removal device such as a bone fastener driver that can be easily inserted into the head of a bone fastener, with a resultant positive, complete tri-modal retention of the driver to the fastener, where positive, complete tri-modal retention may include the prevention of each bi-lateral, bi-rotational, and bi-axial divergence of the driver from the fastener.
Another goal of at least one embodiment of the invention is to provide a positive retention driver/fastener system that is operable by a user who prefers to (or must) use only one hand.
A further feature of at least one embodiment of this invention may be to provide a positive retention element that may also facilitate proper alignment of the driver with the fastener.
Another goal of the invention is to enable the application of increased driving torques when necessary or desired without resulting in positional divergence of the driver from the fastener. Such increased torques may not have been possible with prior systems whose designs may have resulted in positional divergence (such as bi-axial, bi-lateral, or bi-rotational slippage) of the driver from the fastener during higher applied torque load operation, or whose designs may have required the application of an improperly high compressive axial force to assure secure driver-to-fastener engagement throughout the driving process.